How to download YouTube videos to Android phone?

I've tried apps from the google play store and none of them work. I would try to download a 1 minute video and it would end up "download unsuccessful." Is there a way I can download YouTube videos to my phone easily?

You might be prompted to switch on an "install apps from outside the Play Store" option; if you are, switch it to on (the warning you'll get looks a bit scary, but you can safely ignore it). When the app is installed, you can turn this off again for safety if you want. Now you should be able to share YouTube videos from the YouTube app with the downloader application (just click the share button on the video you want to download and share it with YouTube Downloader).